Apparatus and method for accumulating metallic strip and the like



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United States Patent Filed Mar. 3, 1966, Ser. No. 531,581 Claims. (Cl.242-55) This invention is a continuation in-part of Ser. No. 324,326filed Nov. 18, 1963, now Patent No. 3,258,212, and relates to animproved apparatus and method for accumulating strip material, and whilethe invention is particularly adapted to the accumulation of metallicstrip and will be so described, it is to be understood fnom the outsetthat the utility of the invention is not so limited and may be appliedto diverse other strip materials wherein accumulation is desired.

More specifically, the instant invention has to do with the solution tothe problem of providing a continuous delivery of strip-usuallywithdrawn from a coil-to a processing line even though it is necessaryto interrupt the feeding of the strip periodically in order to weld orotherwise secure the leading end of a new coil onto the trailing end ofan exhausted coil. In order to accomplish such an operation, movement ofthe two parts to be secured together must be arrested while the ends aresheared and properly aligned and welded together. There may be all sortsof other reasons why the feed of strip may be interrupted for variousperiods of time either accidentally or intentionally and it is thereforethe principal object of the present invention to provide an accumulatingprocedure and apparatus by means of which a substantial quantity ofstrip can be accumulated so that a continuous feed from the accumulatedsupply may be maintained even though the input of strip is temporarilyhalted.

It is a further object of the invention to provide a device which, whenthe feeding of the strip thereto is resumed following an interruption,will reaccumulate sufiicient strip to permit another stoppage of feedwhile still delivering a continuous supply therefrom.

Another important object of this invention is to provide a stripaccumulating device that can be operated without the necessity ofimmersing the coiled strip in a lubricant.

A still further object of this apparatus is to exert a minimum of backtension on the feeding line by reducing the friction resulting from therelative movement of contiguous convolutions.

It is still another object of the invention to provide an apparatus bymeans of which the method herein disclosed may be carried out, whichapparatus takes up a minimum of space since it is extremely compact andwhich requires a minimum capital investment.

These and other objects of the invention which will be described in moredetail hereinafter are accomplished 'by that series of method steps andby that construction and arrangement of parts of which an exemplarydisclosure is made herein. Other advantages than those discussed abovewill be apparent to one skilled in the art upon reading thisspecification and will be made apparent hereinafter.

Reference is made to the drawing forming a part hereof and in which:

FIGURE 1 is a somewhat diagrammatic plan view of the device for carryingout the invention with the accumulator coil in an intermediate loadedcondition.

FIGURE 2 is an enlarged diagrammatic cross-sectional view taken on theline 22 of FIGURE 1.

Briefly, in the practice of the invention there is'provided a tablehaving a central circular fixed portion and an annular rotatableportion. The rotatable portion is provided with actuating means toinitiate its rotation. Fric- Patented Sept. 12, 1967 tional contact ofthe strip being withdrawn from the rotatable portion maintains therotation thereof during its periods of rotation. The rotatable portionis further provided with a plurality of retractable abutments which,when in operative position, contact and restrain a number ofconvolutions of strip material as it is coiled on the rotatable portionof the table. The fixed portion of the table is provided with anabutment or roll cage from which the coiled strip is fed from the devicethrough a strip processing line or the like.

The basic principle of the invention involves the provision on therotatable table of a coil of said strip material of a predeterminednumber of turns. The coil will be disposed with the strip on edge andwill be suitably supported and held in place on the table. Additionalstrip from the decoiler or from the preceding portions of the processingline is fed onto the outside of the storage coil as the table isrotated, and strip is paid off from the inside of the coil and fed to asucceeding portion of the strip processing line. In accordance with thepresent invention, a predetermined number of turns in the storage coilis maintained constant. When the supply of strip being fed to the coilis interrupted, the rotating table is stopped, but the strip continuesto be paid off from the inside of the coil which is in an expandedcondition, i.e., spaced outwardly from the roll cage. At this point itmay be helpful to facilitate understanding of the following descriptionto point out that the coil has in effect, two sets of convolutions, thedispensing or innermost convolutions, and the accumulating or outer-mostconvolutions. In no case should this be interpreted to mean two distinctcoils, but rather a continuous coil in which the outermost set ofconvolutions is spaced from the innermost set. Now, as the strip iswithdrawn from the inside of the coil while the table on which it issupported is held against rotation, the accurnu-' lating convolutionscollapse inwardly one by one against the roll cage 'on the centralstationary table as the coil is in effect tightened or made smaller indiameter. When all of the convolutions have collapsed so that the coilis tight, or if strip input is to be resumed, rotation of the table willbe resumed so that while strip continues to be paid off from the insideof the coil as the table rotates, additional strip will be wound ontothe outside of the coil. Since the outside circumference of the coil issubstantially greater than the inside circumference of the coil, thediameter of the coil will increase and the length of strip in the coilwill also increase until the initial expanded condi tion' of the coil isreestablished. The action of the storage coil is in effect a cyclictightening and loosening without a change in the number of turns in thecoil. When all of the inner or dispensing set of convolutions have beenremoved from the coil, they will have been replaced by a like number ofouter or accumulated convolutions, whereupon the collapsing process willbe repeated.

Referring now in more detail to the drawings, the fixed portion of thetable is indicated at 10 and it is provided with bearings 11 upon whichthe rotating annular table 12 is mounted. Rotating table 12 may be aplanar surface with spaced openings, the need for which will bedescribed later, or it may take on the appearance of a spoked wheel. Thelatter embodiment of the rotatable table may be defined by the outerannular ring 12a and inner annular ring 12b connected by a series ofradial support members 120. The annular rotatable table 12 may beprovided with a flanged surface 13 at its periphery which will becontacted by an actuator 14 forming part of the rotation initiatingmeans 15, which means is adapted to be actuated by a tension limitcontrol device, indicated generally at 30. The control device 30 maycomprise the fixed rolls 31 and 32 and the movable roll 33, the devicehaving a tension spring 34 biasing the roll 33- relative to the microswitch 35. Thus, when all of the convolutions of the coil have collapsedto a tight condition against the roll cage, the tension on the exitingstrip increases, as indicated at 29, and roll 33 is moved toward theswitch 35, so that when contact is made with the switch 35, the rotationinitiating means 15 is actuated and rotation of the table is begun. Itshould be apparent that means 15 may be any appropriate device suitableto kick the table and overcome its inertial resistance to rotate. Forexample, it may be a prime mover, a solenoid operated kicker, or apneumatically operated kicker and may engage the table through a ringgear, a ratchet wheel, or a one-way clutch. Where relatively wide stripor heavy gauge stock is being handled, it will be advisable to use aprime mover to provide a portion of the table driving torque. Thus, aDC. motor having high initial torque may be used to initiate rotation ofthe table, whereupon rotational movement of the table will be maintainedby the pulling movement of the exiting strip supplemented by the motorwhich, under normal operating conditions, will supply a portion of thetorque.

In a preferred embodiment of the invention, the fixed portion of thetable 10 is provided with an abutment means in the form of a roll cageconstituted of a plurality of rollers 17 mounted on vertical axesdisposed in a circle. Inside the roll cage there is provided a pay-offroll 18 which is preferably cylindrical in configuration with its axisinclined from the vertical at an angle suitable to provide clearance ofthe exiting strip over the roll cage. Alternatively, the pay-off rollmay be frusto conical in configuration with its smallest diameterlowermost and mounted perpendicular to the fixed table. In any case, theexiting strip will be initially directed upwardly in the mannerillustrated (FIG. 2), whereupon its path of travel may be altered asdesired by means of suitable sets of guide rolls disposed to provide anydesired change in its path of travel.

The rotatable table 12 is provided with a plurality of retractable coilrestraining abutments or fingers 16. These abutments are pivotallymounted below the surface of table 12 or the plane formed by the uppersurfaces of radial support members 12c. The abutments 16 are pivotallymounted for movement from an inoperative retracted position to anupwardly projecting operative position and are moved by air cylinders 6or similar devices suitable for the purpose. In the disclosedembodiment, the abutments are spring biased to the inoperative positionand air cylinders 6 are connected to a rotating air joint 9 throughconduits 8 to which air under pressure is supplied from a source P.Until the time feeding of the strip to the processing unit substantiallyexhausts the innermost set of convolutions 28, the abutments 16 aremaintained in the upwardly extending or operative position and henceinterrupt the surface of rotatable table 12 so as to restrain theoutermost set of convolutions 27 as they are wound onto the coil.Retracting movement of the abutments 16 is controlled by the strip edgeitself contacting sensing elements 4 which contact the collapsed innerset of convolutions and act to release the abutments as the last of theinner convolutions is withdrawn from the inner portion of the coil. Suchsensing elements will be operatively connected to the valve means 7which may be a solenoid actuated valve operative to release the airpressure to the cylinders 6. Upon being retracted, the abutments nolonger restrain the collapsing movements of said outermost convolution27 of the coil against the rollers 17. The release of the outermostconvolutions is not an explosive type reaction but more in the nature ofa restrained inward peeling of one convolution, then another. It isadvisable to provide the hold-down roller to contact the uppermost edgeof the dispensing innermost convolutions 28 to maintain properpositioning on the table and contact therewith so that the frictioncreated by contact of the strip with the table 12 will maintain therotation thereof as the strip is withdrawn. Rotation will automaticallystop when the innermost convolutions are exhausted and the retractedabutments permit the collapsing of the outermost convolutions. However,if desired, the braking device 3 which is arranged to engage the contactsurface 13 may be actuated, as by means of the sensing means 4, to stopthe rotation of the table.

The strip being processed comes from a coil payoff means (not shown)which may be a decoiler or some preceding portion of the stripprocessing line, the strip being advanced therefrom as indicated by thearrow 19. As the strip is advanced, it passes through a tension limitcontrol device indicated generall at 20, connected to the braking device3, which acts as a stop switch for table 12. The control device maycomprise the fixed rolls 21 and 22 and movable roll 23 urged away fromthe fixed rolls by a spring 24. A normally open micro switch, indicatedat 25, is arranged to be contacted upon movement of the roll 23. Thestrip is threaded around the rolls 21, 22 and 23, in the manner shown,and fed onto the storage coil at 26. The storage coil itself isindicated generally at 27. If there is a break in the incoming strip,the switch 25 will be actuated and the rotation of the table will betemporarily halted. At the same time, the switch 25 will act to closethe valve 7 and hence vent the cylinders 6, thereby freeing theabutments to retract under the influence of their associated springmeans. The accumulating convolutions of the coil are thus released forcollapsing movement, and there is no interruption to the output feedingof the strip even though there has been a break in the incoming strip.The innermost dispensing convolution, indicated at 28a, is peeled offthe inside of the convolutions 28 and caused to pass around the rolls 17of the roll cage and exit between an adjacent pair of the rolls,indicated at 17a, whereupon the strip passes around the pay-01f roll 18and is drawn from the device into a post strip processing line.

In the operation of the device, and assuming the storage coil 27 to bein the condition of FIGURE 1, that is, an intermediate loaded condition,let is be assumed that the supply of strip to the coil at 26 is nowinterrupted, as where the trailing end of the strip is released by thedecoiler. This, of course, reduces the tension on the strip beingsupplied at 19 and the relaxed strip releases the roll 23 to theinfluence of spring 24 which serves to close the switch 25 to therebyactuate brake 3 and hence stop rotation of the table 12. The coil 27will remain in position on the now stationary table 12 due to its ownweight. However, the temporary interruption in no way affects the outputfeeding of the strip to the succeeding portions of the processing lineat 38. Such interruption will also cause the abutments 16 to retractpermitting the accumulating convolutions 27 to converge inwardly, sothat the strip continues to be drawn from the device around the payoffroll 18. Since the table is no longer rotating the innermost convolutionof the accumulating convolutions 27 will be contracted and peeledinwardly so as to collapse against the cage of rolls 17. As the feed outcontinues, succeeding convolutions collapse and slide radially inward asthe coil is in effect tightened. In so doing, and due to the stationarycondition of the table, the coil will retain the original number ofturns but the circumference of the collapsing convolutions will bereduced, thereby providing continued strip output. This action continuesuntil all the accumulating convolutions of the coil have collapsed ontothe roll cage. It will be evident that as the successive convolutions orturns col-.

lapse and slide radially inwardly there will be an ever increasingtension exerted by the exiting strip and at some predetermined level oftension, the tension sensing device 30 will cause the rotationinitiating means 15 to kick table 12 to resume its rotation. As thetable 12 begins to rotate, the now collapsed accumulating convolutionsof the coil become the dispensing convolutions. The retracted abutments16 will move to the operative position,

causing strip being added to the coil to wind about the' abutments toform a new set of accumulating convolutions. When the dispensing set ofconvolutions is completely paid out, a new set of accumulatingconvolutions will have been formed and rotation of table 12 will beStopped.

It will be evident that the rotational speed of the table is directlyrelated to the speeds or demands placed upon it by the post stripprocessing unit beyond 29. Therefore, should an interruption occur inthe post strip processing unit, the tension on the exiting strip will bereduced to zero. Resumed operation will cause an increase in tensionwhich in turn will cause the table to resume rotation and the sensingmeans 30 will activate the kicker means 15. It will be observed that asthe table 12 rotates, the number of turns in the coil sets 27-28 willremain constant because turns will continue to be removed from theinside of the coil as new turns are added to the outside, and for eachturn removed from the inside a new turn is added to the outside. Thismay be thought of as a transfer of convolutions back and forth, i.e.,from accnmulating to dispensing and vice versa. Assume for illustrationpurposes only the following conditions for FIGURE 2. Table 12 issupplying the post processing unit at a rate of 30 ft./min. and containsten collapsed dispensing convolutions having a mean circumference of 18ft., and ten accumulating convolutions, averaging about 50 ft. incircumference. At this point the total accumulation is 680 ft. Thistotal may vary, but the predetermined number of convolutions, twenty inthis example, will remain constant. After one revolution, the totalstrip accumulated will be increased by the difference between therespective circumferences of the dispensing and accumulatingconvolutions. In the example given, the increase is approximatelythirty-two feet. This build up will continue until rotation of table 12is halted. The maximum diameter of the storage coil will bepredetermined in accordance with the requirements of use, and thediameter of the table will be sized accordingly. Normally, the size ofthe fully expanded storage coil will be such that the outer oraccumulating convolutions will contain at least a unit length of strip,such as the entire contents of a standard length coil.

It should be apparent from the foregoing that the accumulator will beessentially automatic in operation and will cycle between the loaded andcollapsed conditions of the storage coil. While normally the controlelements 30 and 20 will coact to start and stop the cycle, it is alsocontemplated that the unit could be stopped at any time or place in itsoperating cycle. Alternatively, a sensing device 36 with a spring biasedarm 37 could be positioned to sense the collapse of the outermostconvolution in the accumulating coil set, such sensing means acting toenergize the rotation initiating means 15. In addition, manual controlswould be provided for use when needed.

It will be understood that the delay time which may be provided willdepend upon a number of variables, such as strip gauge, strip speed,number of turns in the storage coil, and the relative diameters of theexpanded and collapsed coil. By way of example, in an exemplaryembodiment of the invention, a coil of strip 17 inches wide having athickness of 0.060 inch is wound into a coil having 20 turns. The rollcage diameter or inside diameter of the collapsed coil is 6 feet and theaverage diameter of the coil in the expanded condition is 11 feet. Witha strip speed in the processing line of 50 feet per minute, a delay timeof more than 6 minutes is achieved. In other words, in this particularexample the supply of strip to the device may be interrupted for morethan 6 minutes while the strip continues to be supplied to theprocessing line at a constant speed of 50 feet per minute. In order toachieve such a delay time with a conventional lo-op car system, a run of150 feet would be required. It will be clear from the foregoing examplethat the device of the present invention occupies a very small areasince the outside diameter of the expanded storage coil is on] about 11feet.

While the strip width and gauge may be varied widely it is nonetheless asimple matter to determine the d mensions of the storage coil which mustbe provided t give any desired time delay for a particular speed c stripoutput. The following equation may be used fo such purpose:

N=number of turns in coil V=velocity of line output D=mean diameter ofaccumulating convolutions d=mean diameter of collapsed dispensingconvolutions It will also be understood that modifications may bt madewithout departing from the spirit of the invention Thus, if the strip isquite thin and wide, it may be neces sary to provide resiliently mountedidlcr rolls to kee the coil standing on edge without falling. Variousmodifi cations may be made in the control elements whicl govern thestarting and stopping of the table 12. For example, various additionalsafety devices may be included inclusive of additional switch meansforming a part 01 control device 20 which would stop the rotation oftable 12 in the event of excessive tension on roll 23, as where thesupply of strip at 19 would be stopped for any reason. Similarly,tension responsive switch means may be provided to stop feeding movementof the strip at 29 in the event of malfunction in the operation of thetable 1.2. It will be understood that the control device 20 is exemplaryonly and that other forms of sensing and control devices may beemployed. For example, instead of the tension devices 20, a strip enddetector could be employed to sense the trailing end of the stripsupply. Such device could comprise a photoelectric cell or a springbiased switch arm riding in contact with a surface of the strip.

It should now be apparent that this invention has in effect divided theconvolutions of the coil so that the number of laps sliding over oneanother has been greatly reduced during each operating cycle. Dryoperation is therefore facilitated. However, one skilled in the art mayfind it appropriate for a particular application to subject or evenimmerse the coil in a lubricant. Many applications will suggestthemselves to those skilled in the art where the apparatus and method ofthe present invention could be used to provide a time delay. Among suchapplications, for example, would be for what might be termed continuousbox annealing, wherein the coil could be disposed in a furnace and everyelement of the strip would be subject to the furnace temperature for apredetermined length of time.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. The method of providing a continuous strip supply in spite ofintermittent strip feed, which comprises the steps of:

(a) providing a continuous coil having a predetermined number ofconvolutions,

(b) dividing said continuous coil into an inner set of convolutions andan outer set of convolutions lying in spaced relation to each other,

(e) continuously withdrawing strip from the inside of said innermost setof convolutions,

(d) intermittently feeding additional strip to the outside of saidoutermost set of convolutions by rotating said coil during periods ofstrip feed to said coil while holding said outermost set of convolutionsin spaced relation to said intermost set of convolutions to therebybuild up the diameter of said outermost set of convolutions and thelength of strip in said coil,

(e) holding said coil-against rotation during periods of no strip feedto said coil, and during such periods of no strip feed to said coil,releasing said outermost set of convolutions for inward collapsingmovement to replace the innermost set of convolutions withdrawn fromsaid coil.

2. In a strip accumulating device:

(a) an annular rotatable table surrounding a central stationary table,said rotatable table having a planar supporting surface for receiving acoil of strip,

(b) convolutions of which surround said stationary table,

() a fixed annular abutment on said stationary table against whichconvolutions of said coil collapse as strip is withdrawn from the insideof said coil,

(d) retractable abutments mounted for movement relative to rotatabletable, said abutments being spaced outwardly from said centralstationary table and radially disposed with respect thereto, saidabutments being mounted for movement from a retracted position in whichthe planar supporting surface of said rotatable table remainsuninterrupted to an operative position in which said abutments interruptthe planar surface of said table so that convolutions of the coil may bewound thereabout upon rotation of said rotatable table,

(e) means for starting and stopping rotation of said table, and

(f) means for moving said retractable abutments from one position to theother.

3. The strip accumulating apparatus of claim 2 wherein the planarsurface of the rotatable table is defined by a series of radiallyextending support members.

4. The strip accumulating apparatus of claim 3 including inner and outerannular rings connecting the ends of said radial support members.

5. The strip accumulating apparatus of claim 2 wherein the means forstopping rotation of the table includes sensing means operative to stoprotation of said table when the trailing end of the strip from thepre-processing unit is reached.

6. The strip accumulating apparatus of claim 2 wherein the said fixedannular abutment comprises a series of vertical rolls.

7. The strip accumulating device of claim 6 including a cylindricallyshaped pay-off roll angled from the vertical and disposed in the centerof said series of rolls.

8. The strip accumulating apparatus of claim 2 wherein the means toinitiate rotation of the table includes tension sensing means operativeto start rotation of said table when a predetermined tension on theexiting strip is reached.

9. The strip accumulating device of claim 8 where the table rotatingmeans comprises a prime mover to at least initiate rotation of saidtable.

10. The strip accumulating device of claim 2 wherein the means toinitiate rotation of the table includes a contact sensing meansoperative to start rotation of said table when contact with thecollapsing strip is broken.

References Cited UNITED STATES PATENTS 2,318,316 5/ 1943 Lawrence242-55.19 X 2,706,629 4/1955 Cailliot 242-55.19 3,265,321 8/1966 Rahn242--78.1

FRANK J. COHEN, Primary Examiner.

W. S. BURDEN, Assistant Examiner.

2. IN A STRIP ACCUMULATING DEVICE: (A) AN ANNULAR ROTATABLE TABLESURROUNDING A CENTRAL STATIONARY TABLE, SAID ROTATABLE TABLE HAVING APLANAR SUPPORTING SURFACE FOR RECEIVING A COIL OF STRIP, (B)CONVOLUTIONS OF WHICH SURROUND SAID STATIONARY TABLE, (C) A FIXEDANNULAR ABUTMENT ON SAID STATIONARY TABLE AGAINST WHICH CONVOLUTIONS OFSAID COIL COLLAPSE AS STRIP IS WITHDRAWN FROM THE INSIDE OF SAID COIL,(D) RETRACTABLE ABUTMENTS MOUNTED FOR MOVEMENT RELATIVE TO ROTATABLETABLE, SAID ABUTMENTS BEING SPACED OUTWARDLY FROM SAID CENTRAL STATIONRYTABLE AND RADIALLY DISPOSED WITH RESPECT THERETO, SAID ABUTMENTS BEINGMOUNTED FOR MOVEMENT FROM A RETRACTED POSITION IN WHICH THE PLANARSUPPORTING SURFACE OF SAID ROTATABLE TABLE REMAINS UNINTERRUPTED TO ANOPERATIVE POSITION IN WHICH SAID ABUTMENTS INTERRUPT THE PLANAR SURFACEOF SAID TABLE SO THAT CONVOLUTIONS OF THE COIL MAY BE WOUND THEREABOUTUPON ROTATION OF SAID ROTATABLE TABLE, (E) MEANS FOR STARTING ANDSTOPPING ROTATION OF SAID TABLE, AND (F) MEANS FOR MOVING SAIDRETRACTABLE ABUTMENTS FROM ONE POSITION TO THE OTHER.